This invention relates to a lubricating system for an engine and more particularly to an improved lubricating system for a multi-cylinder, two-cycle, crankcase compression, internal combustion engine.
The advantages of two-cycle crankcase compression internal combustion engines for a wide variety of applications due to their simplicity and high specific output are well acknowledged. However, because of the way in which two-cycle engine is normally lubricated, there has been concern about the use of such engines. That is, unlike four-cycle engines wherein the lubrication system for the engine includes a reservoir and the recirculation of the lubricant, with a two-cycle engine it has been the practice to supply lubricant directly to the crankshaft for its lubrication.
More basic two-cycle engines are lubricated simply by mixing lubricant with the fuel and supplying the fuel, lubricant mixture to the engine through the crankcase so that all of the moving components of the engine will be lubricated. Such systems, however, have a number of disadvantages. Specifically, the amount of lubricant required for lubrication varies with engine running conditions and it is not possible with the fuel lubricant mixtures to meet all running requirements. Therefore, the fuel lubricant mixture has been richer in lubricant than necessary so as to ensure adequate lubrication under high speed, high load conditions. However, under other running conditions excess amounts of lubricant are consumed and may be discharged to the atmosphere.
There have, therefore, been proposed direct lubricating systems wherein the lubricant is supplied to the engine in a manner other than by mixing it with the fuel. In these systems the fuel may be introduced into the induction system and/or may be introduced into the engine through the induction system and at other specific points for direct lubrication. With this type of arrangement, it is possible to control the amount of lubricant supplied in response to engine conditions more accurately than when it is mixed with the fuel in a fixed ratio.
However, even the direct lubricating systems have disadvantages and can be improved upon. Specifically, various components of the engine may and do, in fact, require different amounts of lubricant under varying running conditions. The previously proposed systems have not permitted control of the amount of lubricant supplied to the individual components of the engine independently of each other.
It is, therefore, a principal object of this invention to provide an improved lubricating system for a crankcase compression two-cycle internal combustion engine.
It is a further object of this invention to provide an improved lubricating system for a two-cycle crankcase compression internal combustion engine wherein various components of the engine are supplied with differing amounts of lubricant, depending upon their specific needs.
It is a still further object of this invention to provide an improved direct lubricating system for an engine wherein different lubricant supplies are provided for different parts of the engine.
In addition to the individual components of-the engine having different lubricant requirements under the same running conditions, it has also been observed that those components associated with one cylinder of the engine can have different lubricating requirements that those same components but associated with a different cylinder of the engine. This is due to a wide variety of reasons, but nevertheless is a phenomena that is acknowledged. In addition, the relative requirements of lubricant for the same component for different cylinders may not vary in the same relationship as the running parameters.
It is, therefore, a still further object of this invention to provide an improved lubricating system for a multiple cylinder engine of a two-cycle, crankcase compression type wherein the amount of lubricant supplied to the same components of different cylinders can be varied as required.